EP1057842A1 - Polyadducts having hydroxyl and uretdione groups and containing a flow agent, a process for their preparation as well as their use for the preparation of polyurethane powder coatings - Google Patents

Abstract

Hydroxyl- and uretedione-group containing polyaddition products (I) are prepared from isophorone di isocyanate uretedione, aliphatic and/or cycloaliphatic diols and/or other functional group containing diols and contain a flow agent. Hydroxyl- and uretedione-group containing polyaddition products (I) are prepared from: (A) 40-81 wt.% isophoronediisocyanate uretedione; (B) aliphatic and/or cycloaliphatic diols; and/or (C) other functional group containing diols (I) comprises (A)-(C) in a total amount of 14-59.9 wt.% and further contain (D) 0.1-5 wt.% of a flow agent. (I) contains terminal hydroxyl groups and has a functionality of 2 and a number average mol. wt. of 1,500-10,000. Independent claims are also included for: (i) a process for the production of (I) by mixing (A) in presence of (D) with (B) and/or (C) at 50-190 degrees C; and (ii) a non-splitting, transparent or pigmented polyurethane powder paint (II) containing (I).

Description

The invention relates to leveling agents containing hydroxyl and uretdione groups Polyaddition products, a process for their preparation and their use for Production of high-gloss, light and weather-stable powder coating films with less susceptibility to failure of the coating surface after processing the Powder coatings, especially on single screw extruders.

DE-OS 30 30 572 describes a process for the preparation of uretdione groups Polyaddition products and those produced afterwards Products presented. These are reaction products from the Isocyanurate-free uretdione (UD) of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (also isophorone diisocyanate or IPDI for short) - can be produced according to DE-OS 30 30 513 or 37 39 549 - and diols and, if appropriate Mono alcohols or amines. The reaction can be in bulk or in Suitable solvents are present. In practice, they are relevant to the market Sales quantities of this crosslinker class only in a suitable solvent produced under gentle conditions, at around 60 ° C, to the thermal Avoid ring opening during synthesis. The manufacture is in substance So far not come beyond the laboratory scale, because depending on the Crosslinker molecular weight builds up a high viscosity level in the course of the reaction; Temperature increase as a measure for viscosity regulation is, as in DE-OS 30 30 572 listed, limited.

This limit can also be seen in the examples of DE-OS 30 30 572: it is one Molar mass of a maximum of 3,000 or a uretdione / diol molar ratio of 5: 4 a uretdione grade with a free NCO content of 17 and an NCO content of 37.8% by weight. The free NCO content of the isophorone diisocyanate uretdione increases constant total NCO content, d. H. the degree of oligomerization decreases at the same time and thus also the molar mass of the uretdione used, decreases accordingly the molar mass of the polyaddition products containing uretdione groups. The production Polyaddition products containing uretdione groups with high molecular weights applied in the sense of Use, namely as a crosslinker for the production of PUR powder coatings, from above reasons mentioned make little sense. This is also reflected in DE-OS 30 30 539 and 30 30 588 again. In DE-OS 30 30 539 the molecular weights are between 550 and 4,300, preferably between 1,500 and 2,000, the uretdione / diol molar ratios are between 2: 1 and 6: 5, preferably 3: 2 and 5: 4.

In DE-OS 30 30 588 the claimed molecular weights are only insignificant changed, namely from 500 to 4,000, preferably 1,450 and 2,800 in one of the DE-OS 30 30 539 comparable uretdione / diol molar ratio.

Decisive disadvantages of non-cleaving PUR powder coatings according to the teaching of DE-OS 30 30 539 and DE-OS 30 30 588 were the limited possible combinations polymers containing hydroxyl groups: on the one hand - DE-OS 30 30 539 - were high Functionalities - ≥ 3.4 to ≤ 7, preferably 3.7 to 4.5 - required in order for the To achieve high quality PUR powder coatings high network density, the chain-breaking components of the crosslinker can be compensated. On the other hand - DE-OS 30 30 588 - was the free NCO content of the crosslinker contribute that the functionality of the hydroxyl-containing polymers on the free NCO content must be coordinated, avoiding gelling during extrusion and thus suppressing the loss of quality of the coatings. The OH functionality had to be limited to ≥ 2.2 to ≤ 3.5, preferably from 2.5 to 3.4. It was and elaborate investigations are still required to find resin and hardener to coordinate with each other.

The teaching of DE-OS 30 30 572 also contains uretdione groups Polyaddition products with terminal OH groups described using an example and claimed. The scope corresponds to the polyaddition product mentioned above. For the So far, however, the OH-terminated polyaddition products have had a PUR powder coating sector is of no importance as the economic value compared to the other crosslinkers was not given; see Example 5 of DE-OS 30 30 572 compared to the remaining examples. The numbers speak for themselves. These and chemical reasons, namely the uncontrolled polyaddition of the free OH groups with NCO groups, the additionally caused by uretdione cleavage during the synthesis were good reasons to attach no importance to this type of network.

DE-OS 44 06 444 describes hydroxyl- and uretdione-containing polyadducts, which are suitable as crosslinkers for the production of gap-free PUR powder coatings, without the disadvantages mentioned. However, processing is this Polyaddition products with hydroxyl-containing polymers to powder coatings problematic. Especially after the homogenization of the powdered ingredients on single-screw extruders, but also depending on the polymer Twin screw extruders, the surfaces of the coatings are by needle pricks or disturbed crater.

EP-A-0 639 598 describes polyaddition products containing uretdione groups low melt viscosity, which is the problem of surface disturbance in the Do not completely remove powder coating.

The object of the present invention was therefore based on new crosslinkers to find polyaddition products containing hydroxyl and uretdione groups, which are described in Combination with polymers containing hydroxyl groups to form non-cleaving PUR powder coatings can be processed and their coatings are highly flexible and shiny and have no surface defects.

Surprisingly, it was found that the addition of a leveling agent to the polyaddition products containing hydroxyl and uretdione groups, as they are in principle are known (z. B. from DE 44 06 444), the sensitivity of the surfaces of the especially against powder coatings processed on single-screw extruders Disorders such as B. pinpricks or craters eliminated.

A) 40 bis 81 Gew.-% Uretdion des Isophorondiisocyanats,

B) aliphatische und/oder cycloaliphatische Diole
und/oder

C) weitere funktionelle Gruppen enthaltende Diole,

in einer Gesamtmenge von 59,9 bis 14 Gew.-%, wobei das Mischungsverhältnis B) zu C) frei wählbar ist, und eine Komponente auch allein enthalten sein kann,

und

D) 0,1 bis 5 Gew.-% mindestens eines Verlaufmittels,
wobei die Polyadditionsprodukte terminal Hydroxylgruppen tragen, eine Funktionalität von 2 aufweisen und die zahlenmittleren Molmassen zwischen 1500 und 10 000 variieren.

The present invention therefore relates to polyadducts containing leveling agents and containing hydroxyl and uretdione groups, built up from the starting components

A) 40 to 81% by weight uretdione of the isophorone diisocyanate,

B) aliphatic and / or cycloaliphatic diols
and or

C) further functional groups-containing diols,

in a total amount of 59.9 to 14% by weight, the mixing ratio B) to C) being freely selectable, and a component can also be contained on its own,

and

D) 0.1 to 5% by weight of at least one leveling agent,
wherein the polyadducts carry terminal hydroxyl groups, have a functionality of 2 and the number-average molar masses vary between 1500 and 10,000.

The invention also relates to the manufacture of leveling agents containing hydroxyl and uretdione polyadducts, thereby characterized in that the uretdione of isophorone diisocyanate A) in the presence of a several leveling agents D) with diols B) and / or further functional groups containing diols C) are reacted at temperatures of 50 to 190 ° C, the Polyaddition products carry hydroxyl groups, have a functionality of 2 and the number average molecular weights between 1500 and 10,000, preferably 1,500 and 7,000 lie.

The invention also relates to the use of leveling agents containing hydroxyl and uretdione polyadducts Manufacture of non-cleaving, transparent or pigmented PU powder coatings of high quality Reactivity and excellent gloss, made from the blocking agent-free, Leveling agents containing hydroxyl and uretdione group polyadducts, Polymers containing functional groups and those in PUR chemistry usual auxiliaries and additives.

The invention also relates to cleavage-free, transparent or pigmented PUR powder coatings, which contain the leveling agents hydroxyl and Contain polyaddition products containing uretdione groups.

The isocyanurate-free uretdione of isophorone diisocyanate A) is highly viscous at room temperature (viscosity> 10 ⁶ mPa · s), at 60 ° C the viscosity is 13 · 10 ³ mPa · s and at 80 ° C 1.4 · 10 ³ mPa · s s. The NCO content is between 16.8 and 18% by weight, which means that more or less high proportions of IPDI polyuretdione must be present in the reaction product. The monomer content is ≈ 1%. The NCO content of the reaction product after heating to 180-200 ° C is 37.5-37.8% by weight.

For the synthesis of hydroxyl- and uretdione group-containing, according to the invention Polyaddition products are all suitable for use in PUR chemistry Diols B), particularly preferred here: ethylene glycol, 1,4-butanediol, 1,5-pentanediol, Hexanediol-1,6, 3-methylpentanediol-1,5, 2,2,4 (2,4,4) -trimethylhexanediol as well Hydroxypivalic acid neopentyl glycol ester.

Linear hydroxyl-containing diols C) are suitable as further functional groups Polyester, polycaprolactone, polycarbonate, polyether, polythioether, Low amide polyester amides, polyurethanes or polyacetals Molecular weights from 134 to 3 500.

The use of linear hydroxyl groups is particularly advantageous Polyesters with a molecular weight between 250 and 2,000, preferably 300 to 1,500. You are manufactured e.g. B. by combining diols and dicarboxylic acids Preparation of the diols C) are preferred in addition to the above. Diols B) also 2-methylpropanediol, 2,2-dimethylpropanediol, diethylene glycol, dodecanediol-1,12 and trans- and cis-Cyclohexanedimethanol used. Among the preferred dicarboxylic acids aliphatic, optionally alkyl branched dicarboxylic acids such as succinic, adipic, cork, Azelaic and sebacic acid, 2,2,4 (2,4,4) trimethyladipic acid; continue to be too Hydroxycarboxylic acids such as hydroxycaproic acid are included.

The diols are in a total amount of 59.9 to 14 wt .-%, the Mixing ratio B) to C) is freely selectable, and also contain a component alone can be used. The diols are particularly preferred in the weight ratio of 5: 95 to 90:10.

The leveling agents D) are liquid additives based on polyacrylates or silicones (Polysiloxanes). They can be non-functional, or functional groups such as B. Wear hydroxyl groups. Powdery leveling additives based on substrates such as Silicon dioxide adsorbed can also be used. Examples of suitable ones Leveling agents are products with the trade names Acronal®, Additol®, Byk®, Crylcoat®, Disparlon®, DOW®, DER®, Dynoadd®, Edaplan®, Efka®, EPIKOTE®, Lanco Flow®, Modaflow®, Perenol®, Resiflow® and Troy®. Particularly preferred leveling agents are Acronal® 4F, Byk®-356, Byk®-361, Byk® LP-G 6527, Crylcoat® 109, Perenol® F 45, Resiflow® FL 2, Resiflow® FM 4, Resiflow® PV 5, Resiflow® PV 88 and Resiflow® CP 77.

The preparation of the leveling agents containing hydroxyl and Polyaddition products containing uretdione groups can be used both in the solvent and in Substance, that is, solvent-free.

The reaction in the solvent generally takes place at temperatures from 50 to 100 ° C, preferably between 60 and 90 ° C. The diol component is presented and that IPDI uretdione A) added as quickly as possible without the reaction temperature o. g. Borders. The reaction is complete after 30 to 150 minutes. The Leveling agent D) can be present during the reaction as well as after the end Reaction are added Then the solvent is removed. Suitable for this are z. B. evaporation screws, film trudder or spray dryer. The ex post Incorporation of the leveling agent into the solvent produced and in solution liberated powdery polyaddition product containing hydroxyl and uretdione groups also possible.

Suitable solvents are benzene, toluene or other aromatic or aliphatic Hydrocarbons, ethyl acetate such as ethyl acetate or butyl acetate, also ketones such as Acetone, methyl ethyl ketone, methyl isobutyl ketone or chlorinated aromatic and aliphatic hydrocarbons as well as any mixtures of these or others the reactive groups of the composition of inert solvents according to the invention.

To accelerate the polyaddition reaction, those in PUR chemistry can also be used usual catalysts are used. Tin-II and -IV connections. Dibutyltin dilaurate (DBTL) is particularly mentioned here. she are in a concentration of 0.01 to 1 wt .-%, preferably 0.03 to 0.5 % By weight based on the reaction components used.

Another object of the invention is the solvent-free and continuous Preparation of the leveling agents containing hydroxyl and Polyaddition products containing uretdione groups using an intensive kneader, in particular in a single or multi-screw extruder. Solvent-free synthesis is required Temperatures between 120 ° C and 190 ° C. These temperatures are already clear in the retention area for uretdiones, but without resulting in high free isocyanate contents and thus uncontrolled reaction processes could be observed. As beneficial The short reaction times of <5 minutes, preferably <3, were found to be the case here Minutes, especially <2 minutes.

It is also of a fundamental nature that the short-term thermal load is sufficient in order to mix the reactants homogeneously and completely or largely to implement. Then target according to the balance setting cooled and, if necessary, sales are completed.

The reaction products are the intensive kneader in separate product streams fed, the starting components up to a maximum of 100 ° C, preferably up can be preheated to a maximum of 80 ° C. If there are more than two Product flows, these can also be added in bundles. Diol B), others Functional group-containing diols C), leveling agents D) and catalysts can can also be combined into a product stream. The order can also of product flows are handled variably and the entry point for the Product flows may be different.

Known are known for post-reaction, cooling, comminution and bagging Processes and technologies used.

Another object of the present invention is the use of Leveling agent-containing polyadducts containing hydroxyl and uretdione groups for the production of gap-free, transparent or pigmented PUR powder coatings with high reactivity and excellent gloss. Compared to analogue Crosslinkers that do not contain any leveling agents are characterized by those made from them Coatings are surprisingly characterized by the lack of surface defects.

The invention also relates to cleavage-free, transparent or pigmented PUR powder coatings, which contain the leveling agents hydroxyl and Polyaddition products containing uretdione groups and functional groups Contain polymers and other auxiliaries and additives common in PUR chemistry.

Suitable polymers containing functional groups are compounds which wear such functional groups that deal with isocyanate groups during the Implement hardening process depending on the temperature and time, e.g. B. Hydroxyl, carboxyl, mercapato, amino, urethane (thio) urea groups. As Polymers can be polymers, polycondensates and polyaddition compounds be used.

Preferred components are primarily polyethers, polythioethers, polyacetals, Polyester amides, polyureas, epoxy resins with hydroxyl groups in the molecule, Aminoplasts and their modification products with polyfunctional alcohols, Polyazomethines, polyurethanes, polysulfonamides, melamine derivatives, cellulose esters and ethers, partially saponified homopolymers and copolymers of vinyl esters, in particular but polyesters and acrylate resins containing hydroxyl groups.

The hydroxyl-containing polyesters used have an OH functionality of> 2, an OH number of 20 to 200 mg KOH / g, preferably 30 to 150 mg KOH / g, a viscosity of <60,000 mPa · s, preferably <40,000 mPa · s at 140 ° C and one Melting point FROM> 70 ° C to ≤ 120 ° C, preferably from 75 ° C to 100 ° C.

Preferred carboxylic acids for the production of polyesters can be aliphatic, be cycloaliphatic, aromatic and / or herterocyclic in nature and optionally be substituted by halogen atoms and / or unsaturated. As examples of this called: amber, adipine, cork, azelaine, sebacin, phthalic, terephthalic, isophthalic, Trimellite, pyromellite, tetrahydrophthalic, hexahydrophthalic, hexahydroterephthalic, di- and Tetrachlorophthalic, endomethylene tetrahydrophthalic, glutaric, maleic and fumaric acid or - if accessible - their anhydrides, dimethyl terephthalate, Bis-glycol terephthalic acid, further cyclic monocarboxylic acid such as benzoic acid, p-tert-butylbenzoic acid or hexahydrobenzoic acid.

As polyhydric alcohols such. B. ethylene glycol, propylene glycol 1,2 and 1,3, Butylene glycol 1,4 and 2,3, di-β-hydroxyethylbutanediol, hexanediol 1,6, octanediol 1,8, Neopentyl glycol, cyclohexanediol, bis (1,4-hydroxymethyl) cyclohexane, 2,2-bis (4-hydroxycyclohexyl) propane, 2,2-bis- [4- (β-hydroxyethoxy) phenyl] propane, 2-methylpropanediol-1,3, 3-methylpentanediol-1,5, 2,2,4 (2,4,4) -Trimethylhexanediol-1,6, glycerin, Trimethylolpropane, trimethylolethane, hexanetriol-1,2,6, butanetriol-1,2,4, tris (β-hydroxyethyl) isocyanurate, Pentaerythritol, mannitol and sorbitol as well as diethylene glycol, triethylene glycol, Tetraethylene glycol, dipropylene glycol, polypropylene glycols, polybutylene glycols, Xylylene glycol and hydroxypivalic acid neopentyl glycol ester, in question.

The following mono- and polyesters can also be used in principle:

Lactone polyester e.g. B. ∈-caprolactone, or from hydroxycarboxylic acids, for. B. Hydroxypivalic acid, α-hydroxydecanoic acid, α-hydroxycaproic acid, thioglycolic acid; Polyester from the above-mentioned polycarboxylic acids or their derivatives and Polyphenols such as hydroquinone, bisphenol-A, 4,4'-dihydroxybiphenyl or bis (4-hydroxyphenyl) sulfone; Carbonated polyester made from hydroquinone, Diphenylolpropane, p-xylylene glycol, ethylene glycol, butanediol or 1,6-hexanediol and other polyols by conventional condensation reactions, e.g. B. with phosgene or Diethyl or diphenyl carbonate, or from cyclic carbonates such as glycol carbonate or vinylidene carbonate, are obtainable by polymerization in a known manner; Silica polyester; Polyester of phosphoric acid; Polyester of boric acid.

Polysiloxanes, such as, for. B. by hydrolysis of Dialkyldichlorosilanes with water and subsequent treatment with polyalcohols, or those obtainable by adding polysiloxane dihydrides to unsaturated alcohols Products.

Preferred polyesters are e.g. B. also the reaction products of polycarboxylic acids and Glycidyl compounds, such as. B. are described in DE-OS 24 10 513.

Examples of glycidyl compounds that can be used are esters of 2,3-epoxy-1-propanol with monobasic acids that have 4 to 18 carbon atoms, such as Glycidyl palmitate, glycidyl laurate and glycidyl stearate, alkylene oxides with 4 to 18 Carbon atoms such as butylene oxide and glycidyl ether such as octyl glycidyl ether.

As dicarboxylic acids in this process, all of II below listed polycarboxylic acids are used, monocarboxylic acids, which for example listed under III can also be used.

I. Alkohole mit 2 bis 24, vorzugsweise 2 bis 10 C-Atomen, und 2 bis 6 an nichtaromatischen C-Atomen gebundenen OH-Gruppen, z. B. Ethylenglykol, Propylenglykol, Diethylenglykol, Dipropylenglykol, Butandiole, Neopentylglykol, Hexandiole, Hexantriole, Perhydrobisphenol, Dimethylolcyclohexan, Glycerin, Trimethylolethan, Trimethylolpropan, Pentaerythrit, Dipentaerythrit, Mannit;

II. Di- und Polycarbonsäuren mit 4 bis 36 C-Atomen und 2 bis 4 Carboxylgruppen sowie deren veresterungsfähige Derivate, wie Anhydride und Ester, z. B. Phthalsäure(anhydrid), Isophthalsäure, Terephthalsäure, Alkyltetrahydrophthalsäure, Endomethylentetrahydrophthalsäureanhydrid, Adipinsäure, Bernsteinsäure, Maleinsäure, Fumarsäure, Dimerfettsäuren, Trimellithsäure, Pyromellitsäure, Azelainsäure;

III. Monocarbonsäuren mit 6 bis 24 C-Atomen, z. B. Caprylsäure, 2-Ethylhexansäure, Benzoesäure, p-tert.-Butylbenzoesäure, Hexahydrobenzoesäure, Monocarbonsäuregemische natürlicher Öle und Fette, wie Cocosfettsäure, Sojaölfettsäure, Ricinenfettsäure, hydrierte und isomerisierte Fettsäuren, wie "Konjuvandol"-Fettsäure sowie deren Gemische, wobei die Fettsäuren auch als Glyceride einsetzbar sind und unter Umesterung und/oder Dehydratisierung umgesetzt werden können.;

IV. einwertige Alkohole mit 1 bis 18 C-Atomen, z. B Methanol, Ethanol, Isopropanol, Cyclohexanol, Benzylalkohol, Isodecanol, Nonanol, Octanol, Oleylalkohol.

Preferred components are also monomeric esters, e.g. B. dicarboxylic acid bis (hydroxy (alcohol) esters, monocarboxylic acid esters of polyhydric polyols and oligoesters which can be prepared by condensation reactions from raw materials customary in coating chemistry.

I. alcohols with 2 to 24, preferably 2 to 10 C atoms, and 2 to 6 OH groups bonded to non-aromatic C atoms, e.g. B. ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediols, neopentyl glycol, hexanediols, hexanetriols, perhydrobisphenol, dimethylolcyclohexane, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, mannitol;

II. Di- and polycarboxylic acids with 4 to 36 carbon atoms and 2 to 4 carboxyl groups and their esterifiable derivatives, such as anhydrides and esters, for. B. phthalic acid (anhydride), isophthalic acid, terephthalic acid, alkyl tetrahydrophthalic acid, endomethylene tetrahydrophthalic anhydride, adipic acid, succinic acid, maleic acid, fumaric acid, dimer fatty acids, trimellitic acid, pyromellitic acid, azelaic acid;

III. Monocarboxylic acids with 6 to 24 carbon atoms, e.g. B. caprylic acid, 2-ethylhexanoic acid, benzoic acid, p-tert-butylbenzoic acid, hexahydrobenzoic acid, monocarboxylic acid mixtures of natural oils and fats, such as coconut fatty acid, soybean oil fatty acid, ricin fatty acid, hydrogenated and isomerized fatty acids, such as "conjuvandol" -fatty acid and their mixtures can also be used as glycerides and can be reacted with transesterification and / or dehydration .;

IV. Monohydric alcohols with 1 to 18 carbon atoms, e.g. B methanol, ethanol, isopropanol, cyclohexanol, benzyl alcohol, isodecanol, nonanol, octanol, oleyl alcohol.

The polyesters can be condensed in a manner known per se Inert gas atmosphere at temperatures of 100 to 260 ° C, preferably 130 to 220 ° C, can be obtained in the melt or in an azeotropic driving style, such as B. in Methods of Organic Chemistry (Houben-Weyl), Vol. 14/2, 1 - 5, 21 23, 40 44, Georg Thieme Verlag, Stuttgart, 1963 or with C. R. Martens, Alkyd Resins, 51 - 59, Reinhold Plastics Appl. Series, Reinhold Publishing Comp., New York, 1961, is described.

Preferred hydroxyl-containing acrylate resins, which as an OH component can be used are homo- or copolymers, z. B. following Monomers can be selected as starting products: esters of acrylic acid and Methacrylic acid with dihydric, saturated, aliphatic alcohols with 2 to 4 carbon atoms, such as B. 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate and the corresponding methacrylic acid esters; Acrylic acid and alkyl methacrylate with 1 to 18 carbon atoms in the alcohol component, such as. B. methacrylate, Ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, Stearyl acrylate and the corresponding methacrylate esters; Acrylic and methacrylic acid cyclohexyl esters; Acrylonitrile and methacrylonitrile, Acrylamide and methacrylamide; N-methoxymethyl (meth) acrylic acid amide.

a. 0 bis 50 Gew.-% Ester der Acryl- oder Methacrylsäure mit zwei oder mehrwertigen Alkoholen, wie Butandiol-(1,4)-monoacrylat, Hydroxypropyl(meth)acrylat; ferner Vinylglykol, Vinylthioethanol, Allylalkohol, Butandiol- 1,4-monovinylether;

b. 5 bis 95 Gew.-% Ester der Acrylsäure oder Methacrylsäure mit einwertigen Alkoholen, die 1 bis 12 Kohlenwasserstoffatome enthalten, wie z. B. Methylmethacrylat, Ethylacrylat, n-Butylacrylat oder 2-Ethylhexylacrylat;

c. 0 bis 50 Gew.-% aromatische Vinylverbindungen, wie Styrol, Methylstyrol oder Vinyltoluol;

d. 0 bis 20 Gew.-% andere Monomere mit funktionellen Gruppen, wie z. B. Acrylsäure, Methacrylsäure, Crotonsäure, Itaconsäure, Maleinsäure, Fumarsäure, Maleinsäureanhydrid, Maleinsäurehalbester, Acrylamid, Methacrylamid, Acrylnitril oder N-Methylol(meth)acrylamid sowie Gycidyl(meth)acrylat, wobei der Anteil der Gruppe a. und/oder b. mindestens 5 Gew.-% betragen.

Copolymers of are particularly preferred acrylate resins

a. 0 to 50% by weight esters of acrylic or methacrylic acid with dihydric or polyhydric alcohols, such as butanediol (1,4) monoacrylate, hydroxypropyl (meth) acrylate; also vinyl glycol, vinyl thioethanol, allyl alcohol, butanediol 1,4-monovinyl ether;

b. 5 to 95 wt .-% ester of acrylic acid or methacrylic acid with monohydric alcohols containing 1 to 12 hydrocarbon atoms, such as. B. methyl methacrylate, ethyl acrylate, n-butyl acrylate or 2-ethylhexyl acrylate;

c. 0 to 50% by weight of aromatic vinyl compounds, such as styrene, methylstyrene or vinyltoluene;

d. 0 to 20 wt .-% other monomers with functional groups, such as. B. acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, maleic acid semiesters, acrylamide, methacrylamide, acrylonitrile or N-methylol (meth) acrylamide and gycidyl (meth) acrylate, the proportion of group a. and / or b. amount to at least 5% by weight.

The acrylate resins can be produced by the usual methods, i.e. by Solution, suspension, emulsion or precipitation polymerization; but preferred by substance polymerization, which in turn can be initiated using UV light.

The usual peroxides or azo compounds are used as further polymerization initiators applications such as B. dibenzoyl peroxide, tert-butyl perbenzoate or azobiisobutyronitrile used. The molecular weight can e.g. B. with sulfur compounds, such as tert-dodecyl mercaptan, be managed.

Preferred polyethers can e.g. B. by polyaddition of epoxides, such as ethylene oxide, propylene oxide, butylene oxide, trimethylene oxide, 3,3-bis (chloromethyl) oxacyclobutane, tetrahydrofuran, styrene oxide, the bis (2,5) epoxypropyl ether of diphenylolpropane or epichlorohydrin with itself, e.g. B. in the presence of BF ₃ , or by the addition of these epoxides, optionally in a mixture or in succession, to starting components with reactive hydrogen atoms, such as alcohols or amines, for. B. water, ethylene glycol, propylene glycol (1,3) or - (1,2), pentamethylene glycol, hexanediol, decamethylene glycol, trimethylolpropane, 4,4'-dihydroxydiphenylpropane, aniline, ammonia, ethanolamine, ethylenediamine, di (β-hydroxypropyl) -methylamine, di- (β-hydroxyethyl) aniline, hydrazine and also hydroxyalkylated phenols, such as. B. Di- (β-hydroxyethoxy) resorcinol.

Likewise, polyurethanes and / or polyureas containing hydroxyl groups can be used become.

Mixtures of several substances can of course also be used as polyhydroxyl compounds be used.

The mixing ratio of the hydroxyl-containing polymers and those of the invention Leveling agent-containing polyadducts containing hydroxyl and uretdione groups (Crosslinking agent) is usually chosen so that on an OH group 0.5 - 1.2, preferably 0.8-1.1, very particularly preferably 1.0 NCO group.

In order to increase the gelling speed of the thermosetting PUR powder coatings, one can Add catalysts. Organotin compounds such as are used as catalysts Dibutyltin dilaurate (DBTL), Sn (II) octoate, dibutyltin maleate etc. The amount of added catalyst is 0.05 - 5 wt .-% based on the amount of Powder coating.

The flow control agents containing hydroxyl and uretdione groups Polyaddition products are used for the production of PUR powder coatings with the appropriate hydroxyl-containing polymer and optionally catalysts as well as pigments and fillers mixed. The invention is essential further addition of solid or liquid leveling agents. To achieve Coatings with trouble-free surfaces are not enough, the whole Amount of leveling agent in the polyaddition product containing hydroxyl and uretdione groups to incorporate. In the case of liquid leveling agents, it is added as a masterbatch with the hydroxyl-containing polymer. The amount of leveling agent in the Crosslinker and in the resin, based on the total amount of powder, is up to 3 % By weight. All ingredients of the powder coating are homogenized in the melt. This can be done in suitable units, such as. B. heated kneaders, preferably however, by extrusion, with upper temperature limits of 130 to 140 ° C should not be exceeded. The extruded mass opens up after cooling Room temperature and after suitable comminution to the ready-to-spray powder grind. The application of the ready-to-spray powder to suitable substrates can by the known methods, such as. B. by electrostatic or tribostatic Powder spraying, sintering, electrostatic sintering. After this The coated workpieces are applied in powder form for curing for 60 to 10 minutes to a temperature of 160 to 220 ° C, preferably 30 to 10 minutes 180 to 200 ° C, heated. Loss of reactivity compared to PU powder coatings, there are no leveling agents in the crosslinker.

The products according to the invention, the process of the products according to the invention and the PUR powder coatings according to the invention and the process for producing the PUR powder coatings according to the invention are described below with the aid of examples described.

Examples A Preparation of the leveling agents containing hydroxyl and polyaddition products containing uretdione groups A 1 uretdione of isophorone diisocyanate A)

frei: 16,8 - 18,5 Gew.-%    gesamt:    37,0 - 37,8 Gew.-%

The IPDI uretdione produced by the known method has the following NCO characteristics:

free: 16.8 - 18.5% by weight total: 37.0 - 37.8% by weight

A 2 further functional groups-containing diols C) General manufacturing instructions

The starting components - cf. Table 1 - are placed in a reactor and heated to ≈ 140 ° C using an oil bath. After most of the substances have melted, 0.1% by weight of di-n-butyltin oxide is added as a catalyst. The first elimination of water occurs at 150 to 160 ° C. The temperature is raised to 180 ° C to 190 ° C within 2 to 3 hours and the esterification is completed for a further 8 to 10 hours. The bottom product is stirred throughout the reaction time and a gentle stream of nitrogen is passed through the reaction mixture. The acid number of the polyester was always <2 mg KOH / g. Diols C) containing further functional groups Example No. Output components Characteristics AS [mol] NPG [mol] P [mol] HD [mol] OH number [mg KOH / g] Viscosity [25 ° C] [mPa · s] A 2.1 4th 3rd - 2nd 106 ± 7 ≈3500 A 2.2 1 2nd - - 335 ± 15 ≈1500 A 2.3 1 - 2nd - 217 ± 10 nb A 2.4 Polycaprolactone Capa 200 (Interox) 216 Melting range 18-23 ° C

AS:

Adipinsäure

HD:

Hexandiol-1,6

NPG:

Neopentylglykol

P:

Pentandiol-1,5

n.b.:

nicht bestimmt

The abbreviations in table 1 mean:

AS:

Adipic acid

HD:

Hexanediol-1,6

NPG:

Neopentyl glycol

P:

Pentanediol-1.5

nb:

not determined

A 3 containing leveling agents containing hydroxyl and uretdione groups Polyaddition products General manufacturing regulations A 3.1 From solvent

The diol component B) and / or C) - cf. Table 2 - the catalyst (0.03 - 0.5 % By weight DBTL) and the leveling agent (0.1 - 5% by weight) are dissolved in Solvent, placed in the reactor with vigorous stirring and an inert gas atmosphere the calculated amount of IPDI uretdione, dissolved in the solvent, becomes so fast added that the reaction temperature does not exceed 100 ° C. The implementation is checked by titrimetric NCO determination; it is after 1 to 3 Hours ended. The solvent is then removed, the product is cooled and crushed if necessary.

A 3.2 Solvent-free

The IPDI uretdione was placed in the feed housing of a twin-screw extruder fed at a temperature of 60 to 110 ° C, while the diol component B) and / or C) - cf. Table 2- with a temperature of 25 to 110 ° C was added. The leveling agent (0.1 - 5% by weight) was metered in separately. The uretdione or the diol component optionally contained the required amount of catalyst from 0.03 to 0.5% by weight of DBTL based on the end product.

The extruder used consisted of ten casings, five of which Heating zones. The temperatures of the heating zones were subject to a wide range - between 50 and 180 ° C - and could be controlled individually. All Temperatures were target temperatures, the regulation took place in the housings through electrical heating and pneumatic cooling. The nozzle element was heated by oil thermostat. The speed of the twin screw, built with Conveying elements, was between 50 and 380 U / min.

The reaction product, which is obtained from 10 to 130 kg / h, was either cooled, then crushed or formed and bagged, or already the melt formed, cooled and bagged.

The physical and chemical characteristics of the inventive process products and the molar compositions are summarized in Table 2.

B:

Butandiol-1,4

E:

Ethylenglycol

Eg:

Hydroxypivalinsäureneopentylglykolester

HD:

Hexandiol-1,6

P:

Pentandiol-1,5

TMH-d:

2,2,4 (2,4,4)-Trimethylhexandiol- 1,6

Tg:

Glasumwandlungstemperatur

VLM:

Verlaufmittel in Gew. -% bezogen auf die Zusammensetzung

The abbreviations in table 2 mean:

B:

1,4-butanediol

E:

Ethylene glycol

Eg:

Hydroxypivalic acid neopentyl glycol ester

HD:

Hexanediol-1,6

P:

Pentanediol-1.5

TMH-d:

2,2,4 (2,4,4) -trimethylhexanediol-1,6

Tg:

Glass transition temperature

VLM:

Leveling agent in% by weight based on the composition

B polyester

The following Table 3 gives an overview of the market polyesters used for the formulation of PUR powder coatings. Commercially available polyester Ex. B Manufacturer country description Chemical and physical characteristics OH number mg KOH / g Acid number mg KOH / g Melting range ° C Glass transition temperature ° C Viscosity at 160 ° C mPa · s 1 Hoechst AG Italy Alftalat AN 739 55-60 2-4 82-90 > 50 24-29,000 2nd DSM Netherlands Uralac P 1460 38-41 4-4.5 70-75 50 40,000 3rd UCB Belgium Crylcoat 240 26-31 3-4 74-80 > 50 33-38,000

C polyurethane powder coatings General manufacturing instructions

The crushed products, i.e. H. Leveling agents containing hydroxyl and polyaddition products containing uretdione groups, polyester, leveling agent masterbatch, if necessary, catalysts, if necessary, with the white pigment in one Milling pan intimately mixed and then in a single screw extruder Buss homogenized up to a maximum of 130 ° C. After cooling, the extrudate broken and ground with a pin mill to a grain size <100 µm. The powder produced in this way is produced using an electrostatic powder spraying system at 60 KV applied to degreased, possibly pretreated iron sheets and in one Circulating air drying oven baked at temperatures between 160 and 200 ° C.

Leveling agent masterbatch

There are 10 weight percent of the leveling agent - a commercial copolymer of butyl acrylate and 2-ethylhexyl acrylate - in the corresponding polyester in the The melt is homogenized and crushed after solidification.

Catalyst masterbatch

There are 5 percent by weight of the catalyst DBTL in the corresponding Polyester homogenized in the melt and crushed after solidification.

SD = Schichtdicke in µm

HK = Härte nach König (sec)    (DIN 53 157)

HB = Härte nach Buchholz    (DIN 53 153)

ET = Tiefung nach Erichsen    (DIN 53 156)

GS = Gitterschnittprüfung    (DIN 53 151)

GG 60° -Winkel = Messung des Glanzes n. Gardner    (ASTM-D 5233)

Imp rev. = Impact reverse in inch·lb    (DIN EN-ISO 6272)

The abbreviations in the following tables mean:

SD = layer thickness in µm

HK = hardness according to König (sec) (DIN 53 157)

HB = hardness according to Buchholz (DIN 53 153)

ET = Erichsen cupping (DIN 53 156)

GS = cross cut test (DIN 53 151)

GG 60 ° angle = measurement of gloss according to Gardner (ASTM-D 5233)

Imp rev. = Impact reverse in inchlb (DIN EN-ISO 6272)

Claims (23)

Leveling agent-containing polyadducts containing hydroxyl and uretdione groups, built up from the starting components A) 40 to 81% by weight uretdione of the isophorone diisocyanate, B) aliphatic and / or cycloaliphatic diols
and or C) further functional groups-containing diols, in a total amount of 59.9 to 14% by weight, the mixing ratio B) to C) being freely selectable, and a component can also be contained on its own, and D) 0.1 to 5% by weight of at least one leveling agent,
wherein the polyadducts carry terminal hydroxyl groups, have a functionality of 2 and the number-average molar masses vary between 1,500 and 10,000. Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claim 1,
characterized,
that as diols B) ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol-1,5, 2,2,4 (2,4,4) -trimethylhexanediol or hydroxypivalic acid neopentylglycol ester are used become. Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claims 1 to 2,
characterized,
that as further functional group-containing diols C) linear hydroxyl-containing polyesters with a number average molecular weight between 250 and 2,000 are used. Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claims 1 to 2,
characterized,
that as further functional group-containing diols C) linear hydroxyl-containing polycaprolactones, polycarbonates, polyethers, polythioethers, polyesteramides, polyurethanes and / or polyacetals with a number average molecular weight of 134 to 3,500 are used. Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claims 1 to 4,
characterized,
that diols B) and C) are used in a weight ratio of 5:95 to 90:10. Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claims 1 to 5,
characterized,
that liquid or solid additives based on polyacrylates or silicones are used as leveling agents D). Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claim 6,
characterized,
that as leveling agent D) products with the trade names Acronal®, Additol®, Byk®, Crylcoat®, Disparlon®, DOW®, DER®, Dynoadd®, Edaplan®, Efka®, EPIKOTE®, Lanco Flow®, Modaflow®, Perenol ®, Resiflow® or Troy® can be used. Leveling agent-containing polyadducts containing hydroxyl and uretdione groups according to Claim 7,
characterized,
that as leveling agent D) Acronal® 4F, Byk®-356, Byk®-361, Byk® LP-G 6527, Crylcoat® 109, Perenol® F 45, Resiflow® FL 2, Resiflow® FM 4, Resiflow® PV 5, Resiflow® PV 88 or Resiflow® CP 77 can be used. Process for the preparation of the leveling agent-containing polyaddition products containing hydroxyl and uretdione groups according to Claims 1 to 8,
characterized,
that 40 to 81% by weight of the uretdione of isophorone diisocyanate A) in the presence of 0.1 to 5% by weight of one or more leveling agents D) with 59.9 to 14% by weight of diols B) and / or other functional ones Group-containing diols C) are reacted at temperatures from 50 to 190 ° C., the polyadducts bearing hydroxyl groups, having a functionality of 2 and the number-average molar masses between 1,500 and 10,000. Method according to claim 9,
characterized,
that the reaction of the compounds A) to D) takes place in solution and this is removed after the reaction. Method according to claim 9,
characterized,
that the reaction of the compounds A) to D) takes place solvent-free in the intensive kneader. Method according to claim 9,
characterized,
that the reaction of the compounds A) to D) takes place solvent-free in a single or multi-screw extruder. Method according to claims 9 to 12, characterized in that
that catalysts are used in a concentration of 0.01 to 1% by weight, based on the raw materials used. Use of the leveling agent-containing polyaddition products containing hydroxyl and uretdione groups according to Claims 1 to 8,
in combination with functional group-containing polymers for the production of non-cleaving transparent or pigmented polyurethane powder coatings. Gap-free, transparent or pigmented polyurethane powder coatings,
characterized,
that they contain leveling agents containing hydroxyl and uretdione polyadducts according to claims 1 to 8, functional group-containing polymers and other auxiliaries and additives. Gap-free, transparent or pigmented polyurethane powder coatings according to claim 15,
characterized,
that leveling agents are used as auxiliaries and additives. Gap-free, transparent or pigmented polyurethane powder coatings according to claim 16,
characterized,
that the leveling agents are contained in a concentration of 0.01 to 3 wt .-%, based on the total amount of the powder coating. Gap-free, transparent or pigmented polyurethane powder coatings according to claims 15 to 17,
characterized,
that hydroxyl-containing polymers are used and is based on an OH / NCO ratio of 1: 0.5 to 1.2. Gap-free, transparent or pigmented polyurethane powder coatings according to claim 18,
characterized,
that an OH / NCO ratio of 1: 0.8 to 1.1 is based. Gap-free, transparent or pigmented polyurethane powder coatings according to claim 18,
characterized,
that there is an OH / NCO ratio of 1: 1. Gap-free, transparent or pigmented polyurethane powder coatings according to claims 18 to 20,
characterized,
that the hydroxyl-containing polymers have a functionality> 2, an OH number of 20 to 200 mg KOH / g, a viscosity at 160 ° C of <60,000 mPa · s and a melting point ≥ 70 ° C and ≤ 120 ° C. Gap-free, transparent or pigmented polyurethane powder coatings according to claims 15 to 21,
characterized,
that catalysts are added to the PU powder coating materials in a concentration of 0.03 to 0.5% by weight, based on the total amount of powder coating material. Gap-free, transparent or pigmented polyurethane powder coatings according to claim 22,
characterized,
that organic tin compounds are added to the PU powder coatings in a concentration of 0.03 to 0.5% by weight, based on the total amount of powder coating.